Referring to FIG. 1, the amplifier gain control circuit 10 comprises a bias circuit 11 and a plurality of stages amplifiers 13, 14, and 15, wherein the first stage amplifier 13 can be used for receiving an input signal, such as a radio frequency (RF) or an analog signal, therefore, the input signal would be amplified by the first stage amplifier 13, the n-1 stage 14, and the n stage amplifier 15 respectively. The bias circuit 11 is respectively connected to each stage of amplifiers 13, 14, and 15 and used for controlling the gain of each stage of amplifiers 13, 14, and 15. For example, the bias circuit 11 will receive an analog gain control voltage (VAGC) and further generate a plurality of bias signals according to the VAGC, wherein the bias signals will be used for controlling the gain of each stage of amplifiers 13, 14, and 15, accordingly, the input signal will be amplified.
The bias circuit 11 controls the gain of each stage of amplifiers 13, 14, and 15 by the analog process in respect of the prior art. However, while the amplifiers 13, 14, and 15 adjust the gain thereof substantially, the internal elements of the amplifiers 13, 14, and 15, such as transistors, will be operated in the nonlinear area easily, therefore, the amplified gain of the output signal will not reach the requirement of linearity, and that will result to the wireless transceiver cannot work in the optimal state.